Oxy-bis-(n-alkylamides) and their use as slip additives

ABSTRACT

WHEREIN X IS 1 OR 2, R is an alkyl group of 4 to 22 carbon atoms and R&#39;&#39; is an alkyl group of 4 to 22 carbon atoms. These compositions exhibit improved slip and block properties in the form of films.   Compositions comprising (A) polyethylene, polypropylene, copolymers of ethylene and Alpha -olefins of more than 2 carbon atoms, copolymers of propylene and Alpha -olefins of more than 3 carbon atoms, copolymers of ethylene and vinyl acetate containing up to about 12 percent by weight vinyl acetate polymerized units or mixtures thereof, and (B) 300 to 20,000 parts per million by weight of an oxy-bis-(N-alkylamide) having the formula

United States Patent [191 Powell Nov. 5, 1974 OXY-BlS-(N-ALKYLAMIDES)AND THEIR USE AS SLIP ADDITIVES [75] Inventor:

[73] Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

[22] Filed: June 26, 1973 [2]] Appl. No.: 373,738

Related U.S. Application Data [62] Division of Ser. No. 142,335, May 11,1971, Pat, No.

Richard James Powell, lrange, Tex.

[52] U.S. Cl. 260/873, 260/326 PQ, 260/882 5. 260/937, 260/949 GB [51]Int. Cl..... C08f 15/00, C08f 19/10, C08f 45/44 [58] Field of Search260/326 PQ, 87.3. 88.2 5. 260/937, 94.9 GB

[56] References Cited UNITED STATES PATENTS 2,938,879 5/1960 Mock et al.260/326 PQ 3,330,796 7/1967 Mock et al. 260/326 PO PrimaryExaminer-Joseph L. Schofer Assistant Examiner-Hcrbert J. Lilling whereinx is l or 2, R is an alkyl group of 4 to 22 carbon atoms and R is analkyl group of 4 to 22 carbon atoms. These compositions exhibit improvedslip and block properties in the form of films.

6 Claims, N0 Drawings OXY-BlS-(N-ALKYLAMIDES) AND THEIR USE AS SLIPADDITIVES This is a division, of application Ser. No. 142,335, filed Mayll, 1971, now US. Pat. No. 3,766,269.

This invention relates to oxy-bis-(N-alkylamides). Particularly thisinvention relates to film-forming, carbon chain saturated polymerscontaining oxy-bis-(N- alkylamides).

When a roll of plastic film is unwound or sheets of film are fed from astack of such sheets, it is desirable that there be little cohesion ofthe film to an adjacent layer thereof. One measure of this cohesion iscalled block, which is a measure of the force required to peel one sheetof plastic film from another. Another measure of this cohesion is calledslip, which is a measure of the force required to draw one sheet ofplastic film across another sheet thereof. Generally, a low value forslip and for block means that a low force is required in each of thesetests and therefore that the cohesion is also low. The use of additivesin film resin compositions for the purpose of improving the slip andblock properties of the resultant film is known. Additives which havebeen utilized in polyethylene include oleamide, erucamide,N,N-dialiphatic thiodipropionamide, and stearamide. However, there isstill a need for improved slip and antiblock additives for polyethyleneand for other film-forming plastics.

A composition has been found which when incorporated into a film-formingresin yields a resin which produces a film with improved slip and blockproperties.

. The composition is oxy-bis-(N-alkylamide), having the formula whereinx is l or 2, R is an alkyl group of 4 to 22 carbon atoms and R is analkyl group of 4 to 22 carbon atoms.

When the composition above is incorporated in a film-forming resin, amixture results which comprises (A) a polymer selected from the classconsisting of polyethylene, polypropylene, copolymers of ethylene andalpha-olefins of more than two carbon atoms, co-

wherein x is l or 2, R is an alkyl group of 4 to 22 carbon atoms, and Ris an alkyl group of 4 to 22 carbon atoms.

In the oxy-bis-(N-alkylamides), x is preferably 1 while R and R arepreferably 8 to 22 carbon atoms. R and R can be either saturated orunsaturated alkyl groups but the unsaturated alkyl groups are preferred.

The R and R s which are preferred are oleyl, octyl,

the film-forming polymers is 500 to 2,000 ppm by.

weight. The exact amount of the additive to be used will depend on theparticular additive to be employed, the particular polymer in which itis utilized, and the results desired therefrom.

The film-forming polymers in which the additives of the presentinvention are used include linear and branched polyethylene,polypropylene, copolymers of ethylene and alpha-olefins of more than twocarbon atoms such as propylene, copolymers of ethylene and vinyl acetatecontaining up to about 12 percent by weight vinyl acetate polymerizedunits, copolymers of propylene and alpha-olefins of more than threecarbon atoms, and mixtures of the above. The slip additives of thepresent invention can also be utilized in ethylene/- methacrylic oracrylic acid copolymers or ionomers thereof.

Other of the conventional compounding additives can be present in themixture of the film-forming resin and the slip additive, such as releaseagents, antioxidants, antistatic and other stabilizers. Also, from 500to 5,000 ppm of finely-divided silica can be used together with theoxy-bis-(N-alkylamides) to increase the effectiveness of the additive inhighly glossy films, i.e., films with a gloss greater than 80.

The oxy-bis-(N-akylamides) of the present invention I are prepared bydirect reaction of the appropriate oxy acid such as oxydiacetic acidand'appropriate amine.

The oxy-bis-(N-alkylamides) additives of the present invention can beincorporated intothe film-forming composition by conventional methodssuch as by injecting the additive into an extruder as a melt or in asolution or dry blending the polymer granules with the additive and thenextruding the blend. Also, a concentrate of the additive in a polymercan be formed and then added to the remainder of the resin via anextruder. Other mixing equipment can be used such as a Banbury Mixer ora roll mill.

The resulting mixture can be subjected to any of the conventionalfilm-forming processes such as blowing, chill rolling, or water bath toform films which are useful for wrapping, etc. and which exhibitimproved slip and blocking properties, generally without sacrificing thevisual characteristics of the film as measured by gloss and haze. I

The following examples are meant to illustrate but not limit theinvention. All parts and percentages are by weight unless otherwisespecified. In the Examples, the slip coefficient is determinedsubstantially according to ASTM D-1894-63-Procedure B by using thefollowing procedure: A film-covered metal object, i.e., boat (1.750inches diameter), is pulled over a smooth stationary film surface. Themetal boat which is pulled over the stationary surface is pulled at aconstant rate (20inches/min) by string running over a strain cell. Thestatic and kinetic forces required to move the boat are registered on arecorder. The coefficient of friction is calculated by dividing theforces parallel to the direc tion of motion by that perpendicular to thedirection of motion. A set of weights for the boat is used which willprovide a range of total weight perpendicular to the direction of motionof 0.34 pounds to 2.14 pounds.

In the Examples natural block of blown film is the tendency for theinner surfaces of the collapsed film bubble to stick together. Theprocedure for the test is as follows: A test specimen is carefully cutfrom the roll of blown film as a 2 X 4 inch piece which has two layers.A tab on one layer is clamped stationary and a tab on the opposite endof the other layer is hooked to a string attached to a strain cell. Thetwo layers of film are separated in the direction of the slip, i.e.,parallel to the film surface. The force in pounds required to separatethe two film layers at a constant rate is read from a recorder inpounds. This value is the force in pounds required to separate a surfaceof 8 square inches.

In the Examples, gloss is measured according to AST- M-D5 23 62-T usinga Gardener Gloss Meter and a 20 gloss head. Haze is measured accordingto ASTM-D-l003-6l-Procedure A using a Gardener Haze Meter. Melt index isdetermined according to ASTM D-1238.

EXAMPLE 1 A mixture of 13.4 g. of diglycolic acid (oxy-bis-acetic acid)and 37 g. of laurylamine (molar ratio 1:2) was placed in a 500 ml.beaker and heated-to above the melting point. As the temperature wasincreased, water was evolved as a vapor. The temperature of the mixturewas maintained at about 175C. for 30 minutes. The mixture was stirredoccasionally during the heating period. Gradually the amount of watervapor evolving decreased, and the mixture began to smoke slightly and tocolor. At this point heating was discontinued. The mixture was stirredwhile cooling and formed a crystalline material. No attempt atrecrystallization was made. The yield of oxy-bis-(N-laurylacetamide)based on complete reaction of the starting materials was about 80percent.

EXAMPLE [1 A copolymer of ethylene and vinyl acetate (5.5 weightpercent) was dry blended with each of the additives shown in Table 1such that there was 1,000 ppm by weight of each of the additivespresent. The polymer-additive mixture was melt blended at about 190C. ina 2 inch extruder having a length-to-diameter ratio of 20:1 and fittedwith a mixing torpedo.

The polymer-additive blends were processed into a 1.25-mil blown filmwith a 2 /2 inch extruder having a length-to-diameter ratio of 20:1 andequipped with a 4 inch diameter die. The film was collapsed on passingthrough a nip roll maintained at 40 psi. The melt temperature of thefilm was about 360F. Table 1 indicates the various additives utilizedand their respective melting points as well as valves for slip and blockfor each of the films containing these additives.

TABLE 1 Additive Melt Slip, Block Additive Pt.,F lb/lb lb/8 in None 1.503.36 Oxy-bis-(N-butylacetamide) 0.24 3.54 Oxy-bis-(N-octylacetamide) 2250.18 1.57 Oxy-bis-(N-laurylacetamide) 221 0.30 2.11Oxy-bis-(N-stearylacetamide) 230 0.49 2.60 Oxy-bis-(N-oleylacetamide)185 0.16 2.79 Oxy-bis-(N-(arachidyl behenyl- 'acetamide) 228 1.43 3.10

TABLE l-Continued Additive Melt Slip, Block, Additive Pt.,F lb/lb lb/8in Oxy-bis-(N-erucylacetamide) 187 0.15 1.91Oxy-bis-(N-octylpropionamide) 255 0.32 1.76

EXAMPLE III The procedure of Example 11 was followed except that thepolymer utilized was a copolymer of ethylene and vinyl acetate (3.8weight percent) and the only additive utilized wasoxy-bis-(N-oleylacetamide), the additive being present at 1,000 ppm byweight. The results of various physical property tests on the film areshown in Table 2.

TABLE 2 Physical Property Haze, percent 3.8 Gloss (20) 94 Slip, lb/lb0.10 Block, lb./8 in 2.17

EXAMPLE IV The film was prepared utilizing the same procedure and thesame amount of additive and polymer as in Example II. The slip additiveutilized was oxy-bis-(N- oleylacetamide). In this case, however, silicawas also added to the blend before it was formed into a film. The amountof silica utilized is shown in Table 3.. The results of slip and blocktest on the film as a function of time and silica content are shown inTable 3.

Following the procedure of Example I] two films were prepared which were1.25 mils thick. The first film was made from polyethylene whichcontained 1,000 parts per million by weight oxy-bis-(N- oleylacetamide)and the second film was made from polyethylene which contained 1000parts per million' by weight oxy-bis-(N-oleylacetamide) and 550 partsper million by weight silica. Both films had a slip coefficient of lessthan 0.1 lb/lb. while the block value for both films was less than 0.5lb/8 in.

EXAMPLE Vl Following the procedure of Example II, 1.25 mil blown filmswere made from a blend of ethylene/propylene (approximately 1-3 percentby weight) copolymer with amelt index of 1.5 g/ 10 min. and a density of0.921 gm/cc. and the additives shown in Table 4. A 2

inch extruder with a 20:1 length-to-diameter ratio equipped with a 6inch diameter die was utilized to extrude the film rather than theextruder described in Example ll. The results of various tests on thefilms are also shown in Table 4.

from the class consisting of polyethylene, polypropylene, copolymers ofethylene and a-olefins of more than two carbon atoms, copolymers ofpropylene and a-olefins of more than three carbon atoms, copolymers ofethylene and vinyl acetate wherein the copolymer con- EXAMPLE VIIFollowing the procedure of Example II, a 1.25 mil blown film wasprepared on a l inch extruder which had a 16;1 length-to-diameter ratioand was equipped with a 4 inch diameter die. The film was prepared froman ethylene/propylene (approximately 1-3 percent by weight) copolymerwith a melt index of 2.6 g/ min. and a density of 0.921 gram/cc. whichcontained 1000 parts per million by weightoxy-bis-(N-octylpropionamide). The film had a gloss (20) of 98, a hazeof 4.3 percent, a slip of 0.36 lb/lb and a block of 0.79 lb/8 in EXAMPLEVIII Following the procedure of Example I, oxy-bis-(N- octylacetamide)was prepared from a mixture of 13.4 g. of diglycolic acid and 25.8 g. ofoctylamine (molar ratio of 1:2).

EXAMPLE IX Following the procedure of Example I, oxy-bis-(N-oleylacetamide) was prepared from a mixture of 13.4 g. of diglycolicacid and 50.3 g. of oleylamine (molar ratio of 1:2).

EXAMPLE X Following the procedure of Example I, an oxy-bis-(N-alkylacetamide) was prepared from a mixture of 13.4 g. of diglycolicacid, 25.3 g. of oleylamine, and 25.3 g. of stearylamine.

I claim:

1. A composition comprising (A) a polymer selected from the classconsisting of polyethylene, polypropylene, copolymers of ethylene anda-olefins of more than two carbon atoms, copolymers of propylene anda-olefins of more than three carbon atoms, copolymers of ethylene andvinyl acetate wherein the copolymer contains up to about 12 percent byweight vinyl acetate copolymerized units, and mixture thereof and (B)300 to 20,000 parts per million by weight of the composition having theformula wherein x is 1 or 2, R is an alkyl group of from 4 to 22 carbonatoms, and R is an alkyl group of 4 to 22 carbon atoms.

2. A composition comprising (A) a polymer selected tains up to about 12percent by weight vinyl acetate copolymerized units, and mixturesthereof and (B) 300 to 20,000 parts per million by weight of thecomposition having the formula wherein x is 1 and R and R are alkylgroups selected from the group consisting of oleyl, octyl, and erucyl.

3; The composition of claim 2 wherein (B) is present at a concentrationbetween 500-2,000 parts per million by weight.

4. A composition comprising (A) a polymer selected from the classconsisting of polyethylene, polypropylene, copolymers of ethylene anda-olefins of more than two carbon atoms, copolymers of propylene anda-olefins of more than three carbon atoms, copolymers of ethylene andvinyl acetate wherein the copolymer contains up to about 12 percent byweight vinyl acetate copolymerized units, and mixtures thereof and (B)500 to 2000 parts per million by weight of a composition having theformula H c--cn OCH o H A /x N i l R wherein x is l or 2, R is erucyl,and R is behenyl.

6. A composition of claim 1 in the form'of a film.

1. A COMPOSITION COMPRISING (A) A POLYMER SELECTED FROM THE CLASSCONSISTING OF POLYETHYLENE, POLYPROPYLENE, COPOLYMERS OF ETHYLENE ANDA-OLEFINS OF MORE THAN TWO CARBON ATOMS, COPOLYMERS OF PROPYLENE ANDA-OLEFINS OF MORE THAN THREE CARBON ATOMS, COPOLYMERS OF ETHYLENE ANFVINYL ACETATE WHEREIN THE COPOLYMER CONTAINS UP TO ABOUT 12 PERCENT BYWEIGHT VIMYL ACETATE COPOLYMERIZED UNITS, AND MIXTURE THEREOF AND (B)300 TO 20,000 PARTS PER MILLION BY WEIGHT OF THE COMPOSITION HAING THEFORMULA
 2. A compOsition comprising (A) a polymer selected from theclass consisting of polyethylene, polypropylene, copolymers of ethyleneand Alpha -olefins of more than two carbon atoms, copolymers ofpropylene and Alpha -olefins of more than three carbon atoms, copolymersof ethylene and vinyl acetate wherein the copolymer contains up to about12 percent by weight vinyl acetate copolymerized units, and mixturesthereof and (B) 300 to 20,000 parts per million by weight of thecomposition having the formula
 3. The composition of claim 2 wherein (B)is present at a concentration between 500-2,000 parts per million byweight.
 4. A composition comprising (A) a polymer selected from theclass consisting of polyethylene, polypropylene, copolymers of ethyleneand Alpha -olefins of more than two carbon atoms, copolymers ofpropylene and Alpha -olefins of more than three carbon atoms, copolymersof ethylene and vinyl acetate wherein the copolymer contains up to about12 percent by weight vinyl acetate copolymerized units, and mixturesthereof and (B) 500 to 2000 parts per million by weight of a compositionhaving the formula
 5. A composition comprising (A) a polymer selectedfrom the class consisting of polyethylene, polypropylene, copolymers ofethylene and Alpha -olefins of more than two carbon atoms, copolymers ofpropylene and Alpha -olefins of more than three carbon atoms, copolymersof ethylene and vinyl acetate wherein the copolymer contains up to about12 percent by weight vinyl acetate polymerized units, and mixturesthereof and (B) 500 to 2, 000 parts per million by weight of acomposition having the formula
 6. A composition of claim 1 in the formof a film.